The present invention relates to infusion systems and, in particular, to apparatus for obtaining a zero dead volume, self-sealing connection to a primary flow path, whereby medications can be accurately delivered in a bolus fashion without air embolus, clotting and tissue infection.
Patient infusion systems, whether they be of the gravity type of more sophisticated microprocessor controlled pump type, have undergone a number of improvements over the years with a variety of such systems now being able to more accurately control the delivery rate over time and thereby provide a delivery profile tailored to the patient. As these improvements have occurred, however, a number of problems have been recognized and one of which arises where a patient requires a number of simultaneous infusions of different infusants and/or the administration of a variety of medications in combination therewith. In particular, the rate controllers presently available are not able to accommodate multiple infusants, since each rate controller typically takes into account only the delivery of a single infusant, thus requiring multiple controllers for each different infusant. Even where systems can accommodate multiple infusants, unless relatively sophisticated control circuitry is included therewith, they are unable to accurately assure overlapping delivery profiles for each of the individual infusants. Still further, where one of the infusants is a relatively potent medication, concern arises as to the potential combinational effects of the simultaneously delivered infusants, not to mention the need to be able to accurately delivery the medicant in an undilated form so as to provide the desired effect.
For many critically ill patients and/or patients receiving a number of infusants, an additional problem that oftentimes arises is that only a limited number of access sites are available, thus suggesting the desirability of using a single site to infuse multiple medicants.
As mentioned, a primary concern with the infusion of multiple infusants through a single cannula is that of possible combinational reactions between the infusants and which may be harmful to the patient. Typically, infusant compatability, be it between a potent medication and a bulk volume infusant or some other infusant, is determined by mixing the infusants in a sample container and allowing the infusants to interact over time. If a precipitate forms or a deleterious reaction occurs, indicative of incompatability, the infusants are not administered via a single infusion set. Instead, separate infusion sets and access sites are used.
Such an empirical selection technique, however, ignores the realities of medicant delivery and the discontinuous timing at which many infusants are delivered. That is, with many potent medications, they are delivered in substantially a single bolus over a relatively short period of time so as not to appreciably mix with other infusants. Also, it ignores the fact that many potent medications can be administered along with other marginally compatable infusants, if assurances can be had that the infusants will be isolated from one another until they enter the patient cannula.
Some attempts that have been made to develop multiple infusant delivery systems for a single access site can be seen upon directing attention to U.S. Pat. Nos. 3,566,930; 3,618,637; and 4,191,183. In order to overcome the aforementioned problems, the U.S. Pat. No. 3,618,637 suggests a rotary mixing valve, whereby the infusants are controllably selected and delivered. The U.S. Pat. No. 4,191,183, in turn, suggests a common mixing chamber having a transparent, magnifying window for observing the mixing of the infusants and permitting the viewing thereof for possible precipitates.
Relative to the delivery of more potent medicants in combination with other infusants, other attempts have been directed to various syringe compatible devices and which allow the periodic injection of medicants into the primary flow path. Examples of some devices of this type can be seen upon directing attention to U.S. Pat. Nos. 3,613,663; 3,861,388; and 4,184,489. Each of these devices principally achieves this end via self-sealing septum-like structures which permit the introduction of a syringe needle into the primary fluid flow path. While these devices are relatively simple in construction, medicant delivery requires nursing intervention. Also, the devices have limited lives, since multiple punctures diminish the integrity of the septum-like members.
Still other attempts at developing longer lived devices can be seen upon directing attention to U.S. Pat. Nos. 3,416,567; 3,515,166; 4,439,182; and 3,994,293. There, a variety of infusion systems are disclosed having syringe compatible ports for injecting medicants or relatively small volume infusants at a variety of resilient one-way valves that are cooperatively mounted along the length of the primary infusion set. As disclosed, the one-way valves comprise resilient deflectable flappers and/or ball-type mechanisms. Most pertinent to the present invention is a structure disclosed in the U.S. Pat. No. 3,994,293 which discloses a pre-perforated diaphragm that deflects with the administration of a medicant under pressure. As disclosed, however, a Y-type non-purging connection is contemplated and which includes various cavities between the diaphragm and the primary flow path that can trap air and produce air embolus with the administration of the medicant and/or produce coagulation. Also, the disclosed device is not compatible with infusants deliverable by other than a syringe barrel. Furthermore, it contemplates a relatively large slit in a relatively thin diaphragm member, but which would not be tolerant of the higher back pressures encountered for many infusions.
In order to overcome the foregoing problems, the present invention was developed and which essentially comprises an elastomeric manifold member or catheter having one or more preformed self-sealing slits, each slit coupling an associated inlet port to an outlet fluid flow path. Each infusant is thus isolated from any others via a zero dead volume flow path that opens only under the presence of a predetermined pressure. Depending upon the application, the configuration and durometer of the flow paths can be arranged as desired.
The above objects, advantages and distinctions of the present invention, among others, as well as its construction will be described hereinafter with respect to the appended drawings and a number of alternative embodiments. Before referring thereto, however, it is to be recognized that the following description is made with respect to the presently preferred embodiments only and is not intended to be all inclusive in its description, thus it should not in any way be interpreted to be self limiting.